function feq = FeqStandardD2Q9(k,rho,u1,u2)

e = [0,0;1,0;0,1;-1,0;0,-1;1,1;-1,1;-1,-1;1,-1];
w = [4.0/9,1.0/9,1.0/9,1.0/9,1.0/9,1.0/36,1.0/36,1.0/36,1.0/36];

eu = e(k,1)*u1+e(k,2)*u2;
uv = u1*u1+u2*u2;
feq = w(k)*rho*(1+3*eu+4.5*eu*eu-1.5*uv);

end